Duplicate Boy (Ord Quelu of the planet Lallor) is a fictional superhero in the DC ComicsUniverse first appearing in a story by science fiction writer Edmond Hamilton in Adventure Comics #324 (September 1964). Hamilton had created a backstory for Duplicate Boy, who was first submitted as a super hero concept to DC comics by a young fan, Thea Temple, in 1963, who received acknowledgment from the company. Duplicate Boy appeared as a supporting character in the Legion of Super-Heroes titles, set approximately a thousand years in the future, and is one of the most powerful beings in that time-frame.

Duplicate Boy is a member of the Heroes of Lallor which operates in the 30th century along with the Legion of Super-Heroes, with whom he has teamed up on occasion. He was romantically involved with Legionnaire Shrinking Violet for many years. When she is kidnapped and replaced by Yera, a Durlan impostor who starts a romantic relationship with Colossal Boy, he travels to Earth to confront him. Busy fighting Colossal Boy, he is knocked unconscious by another Legionnaire, Ultra Boy. Recovering, he then confronts Violet and in a fit of rage stated that "she's not the girl I fell in love with", and then flew away. This was later retconned to indicate that he realized Violet was an impostor, but she convinced him not to mention this to anyone. When Violet is freed from captivity some time later, she dumps him for this act.

Duplicate Boy can duplicate any superpower he has ever encountered, and is able to duplicate more than one at a time as well. Thus, he is potentially more powerful than every other superhero in the 30th century, including each member of the Legion of Super-Heroes. However, Nemesis Kid, who has the power to defeat any single adversary, theoretically could defeat him.

His main limitation was his intelligence, as he often would "forget to be invulnerable". For whatever reason he was never depicted as trying to duplicate intelligence powers (e.g., Brainiac 5) that might help him deduce what powers would be most effective, instead usually relying on Evolvo Lad's strategems or none at all. He once tried to take on Validus by duplicating the "Validus Power", which caused him to fall unconscious.